The business of oil exploration has reached the point where it may reach and tap the significant oil deposits that are present under the ocean floor. For the drilling and production operations that occur at sea, oil platforms are used to help the men and equipment necessary for this work. These platforms may typically have legs or bracing members that support the upper structures on the sea floor. While these support members keep the upper deck structure a sufficient height above the main water surface, they still are exposed to the development of marine organisms on structural members in the surge zone (i.e., that zone defined by the high and low water marks). Marine crustaceans and other small marine animals will affix themselves to structures such as platform legs and members and then grow to a substantial size. The growth rate of these organism may be up to 3/4 inch per month and may easily accumulate to a thickness of approximately 14 inches. Of this increased biomass, much of it may be hard growth, which is very difficult to remove.
This marine growth build-up may cause several things to happen, for instance, the member's cross-section may be considerably increased or the member itself may begin to corrode or deteriorate. When the diameter of a piling or member is increased, it presents that much more area to be effected by wave action. This will increase the loads that the support member has to bear and thus makes them more susceptible to damage by storm waves. When the members start to deteriorate due to the biofouling, this compounds a problem.
One common method for removing this material is to have divers simply scrape off the accumulated mass of growth. This, obviously, has its drawbacks. It is expensive for equipment and manpower, the procedure is slow and time consuming, divers may be an added safety risk, etc. Chemical means may also be employed to kill or reduce the attachment of marine organisms to piling surfaces and when carried in a sleeve housing they may provide for a way to protect the pilings without being washed away. U.S. Pat. No. 3,719,049 describes an inflatable sleeve which may carry corrosion resistant materials or rust inhibitors. U.S. Pat. No. 3,661,506 discloses a housing with an inner membrane that carries an anti-foulant and an outer membrane to prevent the dilution of the anti-foulant. However, these methods may introduce toxic biocides into the marine environment or may introduce other possible aquatic contaminants. Cladding is another alternative. A sleeve or winding may be retro-fitted to the pile by wrapping the pile with an external layer (see U.S. Pat. No. 3,655,445). This cladding may simply be a mechanical seal or may be designed to allow the leaching of heavy metal ions (such as copper) into the surrounding area to inhibit marine growth. However, both of these types of cladding may prove to be expensive. Marine growth would still occur so that the wrapped material would have to be changed at some point in time. The cladding with the heavy metal ions would further present a problem of introducing of pollutants and biocides to the environment. In short, no one method may be safe, cheap, and non-toxic.
For the reasons noted above, the purpose of this invention is to create a device that may remove marine encrustation from an offshore platform. It is a further object of this invention to perform this task cheaply, efficiently, and without toxic substances.